Google says one aim is to "bring the world's lost literature back to life"
Google has offered concessions to European publishers who are concerned about the Internet giant's plans to put books into a massive online library.
Material which is out of print in the US, but still available for sale elsewhere, will not be added to Google Books, unless consent is granted.
Google has already digitised millions of out-of-print titles.
The European Commission wants concerted action to allow more books in Europe's national libraries to be scanned.
Only 1% of the holdings in national libraries across the 27 EU members states have been digitised - and complex copyright laws are partly blamed.
"We also need to take a hard look at the copyright system we have today in Europe," said a statement from the European Commission, as hearings got under way in Brussels to assess the latest Google plans.
The Google scanning project has so many more titles than any comparable scheme that many publishers and booksellers fear it will exploit a monopoly position.
In the US, copyright holders get 63% of the price of each book printed to order from Google Books, with the Internet service retaining the remaining 37%.
Out-of-copyright books are available free of charge.
Under the new deal, Google will have to negotiate rights with individual European publishers and authors.
Millions of out-of-print books have already been digitalised
The original plans caused concern because books out-of-print in the US would have been added to Google Books, even though they might be in print and for sale elsewhere, in English or other languages.
"People have described it as a big land grab," said Philip Jones of the UK book trade magazine, The Bookseller.
"Publishers want to see more clarity."
Google also proposes to add a European publisher and a European author to the board of its Books Rights Registry.
Google Books scanning director Don Clancy said the project would offer scanned versions of books to similar organisations, such as Europeana, backed by the EU.